Size controllable preparation of sphere-based monolayer CdS thin films for white-light photodetectors

Abstract CdS has attracted great attention in optoelectronic devices due to its various band gaps and tunable morphologies. Most of the previously reported works were focused on one-dimensional nanostructured CdS-based photodetectors owing to their relatively fast photosensitivity, high photoresponse ratio, and low photoresponse time. However, the poor repeatability, low absolute photocurrents, and deficiency for large-scale production greatly limit their further applications. Moreover, the studies on the photoelectric properties of the CdS nanofilms are considerably limited and the optoelectronic performance of CdS still needs improvement. Herein, we report the CdS nanospheres with adjustable spherical diameters synthesized by a facile hydrothermal method. The reaction times, the reactants mole ratios and the amount of water can significantly influence the sizes of the CdS nanospheres. The monolayer CdS thin films on various substrates were successfully fabricated via an oil-water interfacial self-assembly strategy. Besides, the monolayer CdS thin films on Si/SiO 2 substrates have been tested as nanodevice for white-light photodetectors, which show high stability and multi-wavelength selectivity.